To a bowl, add the flour and salt then whisk and set aside. To a stand mixing bowl add the butter and using the paddle attachment beat the butter on a medium setting for 10 seconds. Add the vanilla extract, icing sugar and continue to beat until well combined.
Add in the flour and continue to mix until a dough forms. Flour a surface then scrap the dough onto the surface and shape it into a rounded log approximately 8 inches long. Wrap the dough in cling film and roll the logged shaped dough back and forth on the surface while it is in the cling film to make it more rounded then refrigerate for 1 hour.
Preheat the oven gas mark 4/350oF/180oC/160oC fan and line a baking tray with baking paper. Remove the dough from the fridge and cut the log into ½ inch thick slices while it is still in the cling film. Remove the cling film from each piece and place each disk shaped shortbread on a baking tray with enough space to spread.
Bake in the lower part of the oven for 15 - 18 minutes until slightly golden. Once baked, allow them cool on the baking tray for 10 minutes then transfer them to a cooling rack using a spatula to cool completely.
Line a baking tray with baking paper and set aside. Add the chocolate to a microwavable bowl and microwave at 20 second intervals until the chocolate has melted. Stir the chocolate at each interval.
Dip half of 1 biscuit into the chocolate and place on the lined baking tray then sprinkle the chopped pecan nuts onto the chocolate. Repeat for all the biscuits then allow the chocolate to set. You can help the chocolate to set quicker by refrigerating the shortbread for 30 minutes. After the chocolate has set, enjoy.